1. Field of the Invention
The present invention relates to an optical disc manufacturing method and an optical disc manufacturing apparatus that are suitably applied to a volumetric optical disc in which a plurality of mark layers are formed in a single recording layer, for example.
2. Description of the Related Art
From the past, circular plate-like optical discs are widely distributed and a CD (Compact Disc), a DVD (Digital Versatile Disc), a Blu-ray Disc (registered trademark, hereinafter referred to as BD), and the like are generally used.
In those optical discs, recording marks are two-dimensionally formed on a thin recording layer formed by sputtering or the like.
On the other hand, in an optical disc apparatus that supports the optical discs as described above, various contents such as music contents and video contents or various pieces of information such as various data items for a computer are recorded on the optical discs. Particularly in recent years, an amount of information has been increased due to achievement of high definition of videos, high sound quality of music, and the like and also needed to increase the number of contents to be recorded on one optical disc, and accordingly the optical disc is needed to achieve a larger capacity.
In this regard, there is proposed an optical disc in which a minute hologram formed by causing light beams of two systems to interfere with each other is set as a recording mark, and the plurality of recording marks are superimposed in a thickness direction of the optical disc, with the result that information whose amount corresponds to a plurality of recording layers is recorded on one recording layer and a large capacity is achieved in the optical disc (see, for example, Japanese Patent Application Laid-open No. 2008-71433, hereinafter referred to as Patent Document 1).